Due to the number of monsters in this level you won't be able to save in Vanilla Doom, if this annoys you, get a port. Also there are some slight HOM problems if you manage to get into a secret area that overlooks a relatively complex area, once against, if this annoys you, use a port! Sometimes monsters teleoport in a little slower than I would like. While they do get to where they are meant to be in the end, it will make speed running 100/100 much harder to pull off.